Regulated DC-output circuits are well known, for use particularly with ordinary commercial alternating current inputs, usually at 60 Hz. However, particularly when such DC-output circuits are providing regulated DC to loads such as remote operating computers and ground stations for satellite tracking systems, and the like, the load on the circuits may vary from time to time, and also the load may be imbalanced. Moreover, it is sometimes desirable that there should be provided a plurality of DC voltages, positive and negative with respect to zero, from a single DC-output circuit device.
Still further, especially when such DC-output circuit devices are remotely located, it is sometimes desirable that they should operate with other than ordinary 60 Hz. inputs. For example, some DC-output circuit devices may be required to operate with 400 Hz. inputs, or even much higher frequency inputs such as 20 to 50 KHz.
Voltage sensing in DC-output circuits is well established, and in circuits according to the present invention the voltage sensing may be similar to the manner of voltage sensing that is taught in other patents issued to the same inventor herein, particularly Canadian Pat. No. 822,798, issued Sept. 9, 1969; Canadian Pat. No. 1,038,033 issued Sept. 5, 1978; or Canadian Pat. No. 1,073,975, issued Mar. 18, 1980. The manner of voltage sensing and the relationship of the voltage sensing to an input power regulating circuit having a saturable reactor or magnetic amplifier or SCR operated devices, are also referred to in those patents.
What the present invention is particularly directed to is the provision of highly regulated DC-output voltage systems having only a single voltage sensing and feedback loop control and regulating circuit, regardless of the number of pairs of balanced DC voltage outputs--with respect to zero-voltage--that may be provided.
Moreover, the present invention is directed to such circuits where the input power may come from relatively high frequency supplies, where in order to preclude unnecessary noise in the output it may be desirable that the circuits should act as switch-mode regulated supplies, with high frequency input.
Still further, circuits according to the present invention may be provided where the input to the circuits may be three-phase or multi-phase, with plural outputs.
The present invention is accomplished by the provision of a regulated direct current output circuit having an alternating current input, with a power regulating means and an output voltage sensing means, where the voltage sensing means is connected in the output of the circuit and controls the operation of the power regulating means, and where the power regulating means controls the power throughput of a transformer which has at least a bifilar wound secondary winding with a centre-tap and at least a pair of first balanced taps with respect to the centre-tap, one on each side thereof. For each tap, there is provided a pair of oppositely facing diodes, connected on one side of each diode to one of the balanced taps and on the other side to the other side of the diode from the other pair of diodes connected to the other tap which has the same polarity. The connected, equal-polarity sides of the pairs of diodes face the output of the circuit. A pair of polarized capacitors is connected to the pairs of output terminals and to the centre, zero-voltage terminal, in positive facing fashion so that the zero-voltage terminal is positive to the negative voltage terminal and negative to the positive voltage terminal, respectively.
Preferably, the diodes are very low threshold diodes such as Schottky diodes.
The above description of a circuit according to the present invention is one which may be used, particularly when the input to the circuit is high frequency. Alternatively, with suitable capacitor input filters, or pi filters the circuit described above may be used with low frequency inputs.
However, where the input to the circuit is at high frequency, it is normal that the connected, equal-polarity sides of the pairs of diodes are, in turn, each connected to one of a pair of bifilar wound chokes. Those chokes have isolated windings on a common core, and are in series with the respect of ones of the pairs of equal-polarity connected diodes. Of course, the polarity of the chokes is also the same as that of the diodes, so as to assure a balanced DC-output.
The output of multi-voltage circuits according to the present invention is closely regulated, despite the fact that the voltage sensing circuit is connected across only a single pair of DC voltage output terminals, with very little loss of regulation, due to the fact that the entire operating circuits are based on the presence of bifilar wound, closely coupled chokes and a bifilar wound secondary winding of the circuit throughput transformer.
Circuits according to the present invention are particularly well adapted, because of their close coupling and well regulated operation, for slaving with similar circuits, without undue amounts of additional control circuitry.